The Operational Generation of Continuous Winds in the Australian Region and Their Assimilation with 4DVAR

Abstract

tmospheric motion vectors (AMVs) have been generated continuously from Multifunctional Transport Satellite 1 Replacement (MTSAT-1R) radiance data (imagery) since 2005, and more recently from MTSAT-2, which are operated by the Japan Meteorological Agency (JMA). These are the primary geostationary meteorological satellites observing the western Pacific, Asia, and the Australian region. The vectors are used operationally, for analysis in the Darwin Regional Forecast Office. The near-continuous AMVs have been stringently error characterized and used in near-real-time trials to gauge their impact on operational regional numerical weather prediction (NWP), using four-dimensional variational data assimilation (4DVAR). The use of these locally generated hourly vectors (the only hourly AMV source in the region at the time) and 4DVAR has resulted in both improved temporal and spatial data coverage in the operational regional forecast domain. The beneficial impact of these data on the Bureau of Meteorology?s (Bureau?s) current operational system is described. After these trials, the hourly MTSAT AMVs were introduced into the Bureau?s National Meteorological and Oceanographic Centre?s (NMOC) operational NWP suite for use by the operational Australian Community Climate Earth System Simulator (ACCESS) regional and global models, ACCESS-R and ACCESS-G, respectively. Examples of their positive impact on both midlatitude and tropical cyclone forecasts are presented.